In recent years, the so-called optical interconnection, a technique for transmitting signals within a system device, or between devices or between optical modules at high speed, has found a wide variety of applications. Here, the optical interconnection refers to a technique in which optical components are used as if they were electric components, and the components are mounted on a mother board or a circuit board for use in a personal computer, a vehicle, an optical transceiver or the like.
Optical modules used for such optical interconnection have a variety of applications, such as intra-device and inter-device connection of components for internal connections of a media converter or a switching hub, an optical transceiver, medical equipment, a testing device, a video system, or a high speed computer cluster.
In such types of optical modules, light that contains communication information emitted from a light emitting element is coupled via a lens to an end face of an optical fiber, which is an example of an optical transmission member, to transmit the communication information via the optical fiber.
To support bidirectional communication, some optical modules include, together with a light emitting element, a light receiving element for receiving the light that contains communication information propagated through an optical fiber and emitted from an end face of the optical fiber.
Conventionally, in such an optical module, variations in output characteristics of light from an light emitting element due to adverse effects of temperature may hinder appropriate transmission of communication information.
Thus, in such types of optical modules, various techniques have been proposed for monitoring light (in particular, an intensity or amount of light) emitted from a light emitting element to stabilize output characteristics of the light emitting element.
For instance, PTL 1 discloses an optical element that includes a reflecting surface (reflecting surface part) around a lens surface (transmitting surface part), the reflecting surface reflecting a part of light emitted from a light emitting element toward a light receiving element, as monitor light.
Furthermore, PTL 2 discloses an optical unit that has an optical surface and includes a total reflecting mirror that totally reflects laser light emitted from a surface emitting laser toward an optical fiber side, and a groove that reflects a part of the laser light emitted from the surface emitting laser as monitor light toward a PD side, in a connecting manner.